Implantation of pacing and defibrillation leads in coronary vessels is becoming increasingly common as atrial and heart failure therapies become more widely accepted. Implanting and stabilizing such leads in the coronary sinus, great vein, and the branch veins is critical to the efficacy of these and other therapies. It is often desirable or necessary to remove leads implanted in cardiac structures, such as the coronary sinus vasculature, for various reasons. Removal of these leads is problematic, especially if coil electrodes are employed on the lead.
Presently, there are no widely accepted extraction tools available for the safe removal of coronary vein leads. Various tools have been developed for removing right ventricular leads and right atrial leads, for example, such as mechanical dissection sheaths, electrocautery sheaths, laser sheaths, and other powered sheaths. Such tools, however, are not suited for use within thin walled vessels. Presently available extraction tools, for example, can only be safely used to enter the proximal portions of the coronary sinus. The risk of significant damage to the vasculature is very high, which can result in cardiac tamponade and death. Consequently, physicians are presently limited to using locking stylets and simple traction as a means of removing coronary vein leads. Use of traction to remove right and left side leads is known to impart significant axial forces on the leads. Excessively high levels of axial loading imparted to conventional leads during lead extraction can result in lead damage or destruction.
Various types of coatings applied to the electrodes have also been considered in order to facilitate easier removal of coronary vein leads. Although the extractability characteristics of leads can be improved using certain lead coatings, use of such coatings has been found to significantly reduce lead stability. For example, coated lead dislodgment rates of 25%-50% have been observed. As such, the gains in lead extractability realizable through use of conventional lead coatings are achieved at the cost of reduced lead stability.
There is a need in the industry for an improved coronary vein lead that exhibits improved extractability characteristics. There exists a further need for such a lead that can withstand relatively high axial loads associated with right and left side lead extraction. The present invention fulfills these and other needs, and provides a number of advantages over prior art approaches.